how to deal with old filament



  • I'm not sure how is this an issue, namely, how the "old filament" has a problem but "old printed part" does not, but obviously it happens so..

    The post is triggered by me using rather old PLA spool (PRC brand - CoLiDo; that I marked 2015, meaning I purchased it in 2015, there is no production data anywhere so maybe it's 2015, maybe even older). The spool was unopened, properly vacuum sealed, vacuum was unbroken as the foil was under tension and I hear the hissing when I opened it, big silika gel package inside... so all "ok", just old date of manufacturing. Directly from the bag I put it into dry box, heated the box for PLA and let it sit there for 5 hours before I start using it... and the behavior is more/less as expected, it prints "ok", tad more stringing than fresh PLA but taking into account this is colido and not some fancy brand that might be unrelated... what is the problem is filament breaking.

    Looks like the piece of the filament that is out of the dry box breaks on it's own without any external force. If I feed the filament directly from the drybox (using eBOX in this case) it works ok, print finish and after 3-4 hours I hear a pop.

    I have short piece of 6mm PTFE tube going from eBOX to a filament monitor and a longer ~40cm piece of 6mm PTFE tube from filament monitor to the extruder. Few hours after print finish a pop/cracking sound can be heard (sometimes it is not audible at all) and you can see that filament inside the PTFE tube, usually in the short piece that's fixed, between eBOX and filament monitor (filament monitor is fixed) closed to the filament monitor broke. Few times filament snapped at 5-6 places in the same time (inside extruder, 2x inside longer ptfe tube, 2x inside short fixed ptfe tube and just at the point of exit from eBOX) ... All this happens when filament is not moving, just sitting there. Not while filament is still warm from the box, but after it cools down. eBOX temp for PLA is 50C (actually it's more like 40-45C as the thin plastic is not a serious insulator but the temp of the heater inside is 50C)

    So the question - how are you handling old filament? Especially PLA and TPU as PP/PE/ABS/HIPS/PETG/PC/PA are not behaving like this in my experience, they do print "uglier" but do not "self break". Normally I don't use old filament at all, but there are "special circumstances" like e.g. now is hard to get any PLA locally as shops did not import new batch and whatever they had was used up (so many ppl printing these shields and masks and.. and many of the shops gave a huge amount of PLA for free for purpose of printing shields and masks)

    Second question is about wth is going on here at all. We mostly accepted that "old filament is not good for printing" but WHY ?! How come old filament becomes brittle and crumbly (I have some old "soft PLA from orbitech" that you cannot touch, if you touch it it breaks into hundreds of pieces, heating, moisturing, drying, nothing helps ... now it is almost 10 years old but .. it is this thing - https://youtu.be/DPW1QP5_Dao note, that's not TPU, it is PLA!)



  • @arhi I read somewhere that light - especially UV light plays a role in making filament brittle. With PLA, more so than moisture. I believe someone once sent me a link to some testing that somebody once did which adds a lot of weight to that theory, but I am unable to find that link.

    Anecdotally, since I moved my printer from my spare bedroom which has windows, to my (insulated) garage which has no windows, I can leave filment on the machine for weeks or even months and it does not become brittle. Whereas, when the machine was in the bedroom, I would have to pull a few metres of filament off the reels and re-load the hot end because it had become brittle to the extent that it would snap away from the hot end and be no longer connected.

    The garage in question is integral to the house, has an insulated door, and a radiator connected to the house heating system. So the temperature and (and likely the humidity) is very similar to the spare bedroom. The only significant difference is that the garage is lit solely with artificial (mostly LED) lighting, rather than natural daylight. That's hardly scientific but maybe there is something in the theory that UV light plays a role in making filament brittle.



  • I've seen more than one spool of PLA that "exploded" - they spontaneously decomposed into fragments a few cm long. Like me, they were probably old and improperlystored. The prints are another matter. No one is going to store them "properly" and they will/do get brittle. I don't know if it's because of moisture absorption or evaporation of some of the chemicals in the plastic. PLA is all but useless for anything except starwars toys and other stuff that will end up in the trash within a few hours of printing.

    I've never seen problems of any kind with TPU. I have the remnant of a spool that I bought about 5 years ago and use it to print small stuff once in a while, and it still prints like new.

    I've seen ABS get brittle, but usually just a few cm on the free end of the spool. ABS adsorbs moisture, which means it sticks to the surface, but doesn't absorb it. I've never seen an ABS print with a bad surface caused by moisture problems, even if the filament wasn't stored properly. I normally store filament in dry boxes with CaCl2 desiccant, but occasionally leave a spool of ABS on my printer for weeks at a time with no problems.

    I had one bad spool (my first, of course) of PETG that printed like it had soaked up a lot of moisture. It also tended to leave charred blobs of plastic stuck to the print in the worst possible places- behavior I've seen to a lesser degree in other spools. I've recently been buying 5 lb spools of PETG from KVP and they print very well- no bubbles, no charred blobs, and minimal hairiness. A lot of people tout PETG as a "replacement" for ABS, but ABS doesn't need to be replaced, PLA does, and PETG is it.



  • i think alex kenis did some more-or-less scientific musing on the subject that supports the UV light theory.



  • Again, more anecdotal stuff but I made my own deck lights to illuminate some steps (they come on at sunset and go off at sunrise). They sit in full sunlight for about half the day and of course are otherwise fully exposed to the elements throughout the year. Hear in the UK it gets down to maybe minus 10 on cold winter nights and up to mid to high 30s on the odd hot summer day. At the time, the only filament I has to hand was transparent PLA, so I printed them with that, fully expecting to have to re-print them with PET-G or something in the near future. That was in 2015 and they appear to be as good as the day that I fitted them. My take on it personally is that PLA is much maligned - maybe brands play a part but I have no idea what I used except to say that it was nothing "exotic".



  • @bearer said in how to deal with old filament:

    i think alex kenis did some more-or-less scientific musing on the subject that supports the UV light theory.

    Yup - that's what who I had in mind. I just did a quick search of his videos and found this https://www.youtube.com/watch?v=Mgyutg9H94Q. Personally, I find the guy annoying to listen to, so I haven't watched the video all the way through myself.



  • The "exploded" PLA spools I've seen were not exposed to UV other than fluorescent lighting in a building. One was in the shipping box. I don't doubt that UV contributes to problems- sunlight destroys everything eventually- but it isn't the only problem, at least for PLA.



  • @deckingman said in how to deal with old filament:

    Personally, I find the guy annoying to listen to, so I haven't watched the video all the way through myself.

    he does have a unique approach to presentation, but he also does seem to know a thing or two so i (rather uncharacteristically) gave the accused the benefit of the doubt. at the very least he seems to know more than me about the stuff he rambles on about.

    That was in 2015 and they appear to be as good as the day that I fitted them.

    don't print much pla so can't comment much; but could it be the geometry of the printed parts just gives it that much more strength compared to the unprinted filament, and that the parts have indeed deteriorated - just not to the point of failure? (destructive testing required i suppose)



  • @bearer said in how to deal with old filament:

    don't print much pla so can't comment much; but could it be the geometry of the printed parts just gives it that much more strength compared to the unprinted filament, and that the parts have indeed deteriorated - just not to the point of failure? (destructive testing required i suppose)

    TBH, I'm surprised at how well they've lasted. They do get a bit of mechanical abuse too. Often trodden on and every week they get a wheeley bin rolled over them - full and heavy in the morning and empty but lighter in the evening. No cracks or distortion noticeable.
    If nothing else, I thought PLA was supposed to "bio-degrade" but there is no sign of that happening yet. Maybe the bio-degrading time frame is measured in decades rather than years 🙂



  • https://www.filabot.com/blogs/news/57233604-the-misleading-biodegradability-of-pla

    " The reality however, is that this process will take several hundred years in a typical landfill. To biodegrade, PLA requires a laundry list of conditions to effectively break down. Specifically - oxygen, a temperature of 140+ degrees, and a 2/3 cocktail of organic substrate. Collectively, these are absent in any scenario outside of industrial composting facilities. This means that PLA plastic will sit in that landfill right alongside ABS and other plastics for a very long time."



  • I think the parts on the Ormerod v1 I procured are printed in PLA (@droftarts will be able to correct me) and they are without an exception suffering from tension creep from the bolts used or outright cracked (probably because the original owner treated them pretty roughly). The original roll of PLA was included and also just disintegrated into tiny scraps after I dried it in an eBox overnight when being fed through the extruder. So, sadly, I had to discard it because printing with it was impossible for me.



  • @mrehorstdmd Ahh OK centuries maybe instead of decades 🙂 That's another urban myth about PLA being busted then.



  • @deckingman said in how to deal with old filament:

    @arhi I read somewhere that light - especially UV light plays a role in making filament brittle. With PLA, more so than moisture. I believe someone once sent me a link to some testing that somebody once did which adds a lot of weight to that theory, but I am unable to find that link.

    Heard the same thing. But for example, the filament in question (what I'm dealing with right now) was in a vacuum foil, inside a cardboard box inside a closed wooden closet, so there is no way UV could access the filament (or any other light) for the 5 years it was "shelved"

    Anecdotally, since I moved my printer from my spare bedroom which has windows, to my (insulated) garage which has no windows, I can leave filment on the machine for weeks or even months and it does not become brittle. Whereas, when the machine was in the bedroom, I would have to pull a few metres of filament off the reels and re-load the hot end because it had become brittle to the extent that it would snap away from the hot end and be no longer connected.

    interesting!



  • @mrehorstdmd said in how to deal with old filament:

    The prints are another matter. No one is going to store them "properly" and they will/do get brittle. I don't know if it's because of moisture absorption or evaporation of some of the chemicals in the plastic. PLA is all but useless for anything except starwars toys and other stuff that will end up in the trash within a few hours of printing.

    I have PLA parts I printed 10 years ago that are still in function!!! and are performing like they did on day one

    I've never seen problems of any kind with TPU. I have the remnant of a spool that I bought about 5 years ago and use it to print small stuff once in a while, and it still prints like new.

    tpu soaks water and can also become crumbly after 3-4 years, seen it few times

    I've seen ABS get brittle, but usually just a few cm on the free end of the spool. ABS adsorbs moisture, which means it sticks to the surface, but doesn't absorb it. I've never seen an ABS print with a bad surface caused by moisture problems, even if the filament wasn't stored properly. I normally store filament in dry boxes with CaCl2 desiccant, but occasionally leave a spool of ABS on my printer for weeks at a time with no problems.

    I'v seen ABS / PETG / HIPS get brittle and/or print bad but you dry it out overnight in a dryer and they behaves like new ... PLA that gone bad does not work ok after drying



  • @deckingman said in how to deal with old filament:

    I thought PLA was supposed to "bio-degrade" but there is no sign of that happening ye

    requires 60C + and acidic envirnonment iirc .. so it's "possible" to "biodegrade" PLA but it will not happen in regular compost



  • @oliof I've seen forum posts from people who left their printers in parked cars for a few hours and came back to discover the PLA parts melted, essentially destroying the printer. If you want to keep something around for a long time, don't take a chance on printing it with PLA. How may objects can you guarantee won't be left in a hot car at some point in their lifetime?



  • @mrehorstdmd that might not be a problem for everyone (welcome to the (other) frozen shi***le of hoth, to qoute ave) but I get what you're saying



  • @mrehorstdmd said in how to deal with old filament:

    don't take a chance on printing it with PLA. How may objects can you guarantee won't be left in a hot car at some point in their lifetime?

    PLA has a bad vibe about temperature but really it's not that worse than other plastic we use. If we talk hot beverages PETG/ABS/HIPS deform too at 90C. IIRC mithbusters shown well over 100C in a car during summer, so again PETG/ABS/HIPS will not do much better. I have PETG from Dasfilament (and I heard from others on this forum with other brands of PETG too) that prints ok at 190C so again not much better than PLA. There's a lot of talk about how PLA is crap and I fell into that trap myself and did not use PLA for many years but in reality, for many purposes PLA is IDEAL material to print with.



  • @arhi I don't know about mythbusters, but I lived in Phoenix for a few years and the plastic parts of my car, primarily ABS (maybe a different formulation than we print with), never melted, and neither did the bracket for holding my GPS unit or the GPS unit's housing. OK, no boiling water in printed plastic cups, that's easily avoided, since prints are usually not watertight anyway. I'd worry more about boiling water leaking on my hands and burning me more than I'd worry about the cup melting. I have put ABS prints in my dishwasher for a few cycles and they came out unscathed.

    I'm not sure how well PETG holds up in a hot car. Maybe not much different than PLA. I'll go put a print out in my car now and see how it goes.



  • @mrehorstdmd I lived in LA for a year, ABS holder for a nokia phone (not printed but injection m.) was bent beyond recognition. HDPE cup colder too (not the factory one). Here in Belgrade we have 43-45C days during summer, never measured temperature inside the car but have PLA parts that survived years (I did not expect them to), I often mention my PLA holder for external thermometer sitting outside for 7th year now, direct sunlight, easily over 60C during summer, easily -20 during winter (not every winter, not every day but) and is still going strong like day1, it is not colored any more, color is gone, but the part itself changed less than the plastic casing of the wireless sensor itself. You need 180+ for PLA to really make a mess, it will lose strength and bend at high temps but so will most other thermoplastics, that's why most of the stuff in your car is made from PC or better; pet, abs, hips... not that much

    Anyhow PLA is not that "pure" material, there is PLA and there is PLA so...

    What's much more important than temperature resistance of thermoplasts is this difference in aging of filament vs printed parts. It's different - A LOT different and I don't see a reason why



  • @mrehorstdmd I am not printing printer parts in PLA -- sorry if I was being unclear. I am reasonably fine with PETG parts, but I'm gravitating towards ASA more and more.



  • I also have problems with the PLA becoming brittle inside a PTFE tube. It's different between different brands. EasyPrint from 3D Prima is worst I have, It's enough for it to be left half a day inside PTFE and it's broken in several places.
    Generally all materials get brittle when they absorb moisture and I dry even my PLA for better end results.


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